The right litter box gives your cat room, privacy and easy access. Consider the box and its position together: a spacious box will be little help if your cat is reluctant to approach it.
Choose a quiet, accessible spot
Choose a calm part of the home, away from busy walkways, washing machines and other sudden noises. Keep the box separate from food and water bowls. Make sure a closed door cannot cut off access, including at night.
Give your cat a clear way in and out. In a home with several cats, another cat should not be able to guard the only route. Place boxes in different suitable locations rather than lining them up together. In a home with several floors, consider access on each floor your cat uses.
Leave enough room to turn and dig
Check the usable inside dimensions, not just the product’s overall size. Your cat needs room to turn, dig and settle without being cramped. Battersea suggests a box around one and a half times the cat’s length from nose to the base of the tail as a starting point.
A kitten may need a low entrance at first and a larger box as it grows. For an older cat or one with limited mobility, easy entry matters more than high sides.
Open or covered?
Watch your own cat’s preference. An open box makes it easier to see the surroundings and notice when cleaning is needed. A covered box may suit some cats, but check the space inside and clean it regularly: smells can build up beneath the cover.
High sides may help contain scattered grains, provided your cat can still get in comfortably. Do not make entry difficult just to keep the floor tidy.
Change one thing at a time
If your current setup works, there is no need to change it for appearance alone. When trying a new box or location, keep the familiar option available and see what your cat actually uses. Avoid changing the box, position and litter at the same time.
If your cat suddenly stops using the box, contact your vet. Check access and cleanliness as well, and never punish your cat.
Further guidance: Battersea: litter box setup and RSPCA: litter boxes.